> It would seem our own generalized intelligence is an emergent property of many, _many_ specialized processes

You can say that about other animals, but about humans it is not so sure. No animal can be taught as general set of skills as a human can, they might have some better specialized skills but clearly there is something special that makes humans so much more versatile.

So it seems there was this simple little thing humans got that makes them general, while for example our very close relatives the monkeys are not.

Humans are the ceiling at the moment yes, but that doesn't mean the ceiling isn't higher.

Science is full of theories that are correct per our current knowledge and then subsequently disproven when research/methods/etc improves.

Humans aren't special, we are made from blood & bone, not magic. We will eventually build AGI if we keep at it. However unlike VCs with no real skills except having a lot of money™, I couldn't say whether this is gonna happen in 2 years or 2000.

It may be a property of (not only of?) humans that we can generate specialized inner processes. The hardcoded ones stay, the emergent ones come and go. Intelligence itself might be the ability to breed new specialized mental processes on demand.